Electric field modulation of electronic structure, charge transfer, and nonlinear optical properties of crocetin for dye-sensitized solar cells

Abstract

Natural sensitizing dyes in solar energy applications have gained attention due to their sustainability, cost-effectiveness, and environmental friendliness. However, enhancing their performance, light-harvesting efficiency, and durability requires a deeper understanding of their structural and electronic properties under solar irradiance. Accordingly, this study explores the electronic structure and nonlinear optical properties of crocetin dye (cis and trans conformers) under varying external electric fields using M06-2X/6-311+G(d,p) model chemistry. The absorption characteristics strongly depend on field intensity, with electron injection efficiency expected to decrease as the field increases. Key nonlinear optical (NLO) parameters, such as dipole moment, polarizability, and hyperpolarizabilities, were calculated at solar irradiance peak frequencies. The NLO properties are wavelength-independent in the infrared region but show significant wavelength dependency in the visible region, increasing substantially near the absorption energy.